[BUG] [kotlin-spring] Type mismatch for post -> required)true

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

(The generation works perfectly fine for typescript-angular)

The generated post request expects a "SearchRequest" object, the generated test provides a "SearchRequest?", thus failing

SearchApiTest.kt:[24,75] Type mismatch: inferred type is SearchRequest? but SearchRequest was expected

@Test
    fun searchPostTest() {
        val searchRequest:SearchRequest? = null
        val response: ResponseEntity<List<SearchResult>> = api.searchPost(searchRequest)

        // TODO: test validations
    }



    fun searchPost( @Valid @RequestBody searchRequest: SearchRequest
): ResponseEntity<List<SearchResult>> {
        return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
    }

Since we use the generated code as a library to be imported in other projects, it's an inconvenience

openapi-generator version

openapi: 3.0.1
penapitools/openapi-generator-cli:v5.3.0

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: Search
  version: v1
servers:
  - url: /api/v1
paths:
  /search:
    post:
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SearchRequest'
      responses:
        "200":
          description: Ad Spaces found
          content:
            application/json:
              schema:
                items:
                  $ref: '#/components/schemas/SearchResult'
                type: array
components:
  schemas:
    SearchRequest:
      type: object
      properties:
        types:
          type: string
    SearchResult:
      type: object
      properties:
        name:
          type: string

Generation Details

image: openapitools/openapi-generator-cli:v5.3.0
docker-entrypoint.sh generate -i ./openapi/openapi.yaml -g kotlin-spring -o ./build --additional-properties=artifactVersion=${VERSION} --additional-properties=artifactId=api-server

Steps to reproduce

Related issues/PRs

Suggest a fix

In case of required, don't use "null" but instead create an empty object?

I hope there is something i'm missing or a quickfix besides skipping tests!

Thanks and best regards

Use the supplied OpenAPI YAML with the documented kotlin-spring generation command to reproduce the failure. Compare the generated SearchApiTest.kt call with the generated searchPost signature and determine how required request bodies should be represented. Done means the generated Kotlin tests compile without the nullable-versus-non-nullable type mismatch.